1. Field of the Invention
This invention relates to a small class of novel trialkoxysilicon compounds which has been found to exhibit mildewcidal activity and to latex paints containing such mildewcidal compounds.
2. Description of the Prior Art
Mildewcidal-induced defacement of paint film and other organic coatings is a serious problem faced by the coatings industry, resulting in several tens of million of dollars of damage annually. Mildew growth destroys coating integrity by a series of microbial (including bacterial and fungal) degradations of paint film components. Hydroxyethyl cellulose, which is often used as a binder in water-based latex paint formulations, is especially susceptible to microbial degradation, and therefore latex paints as a class are especially susceptible to mildew attack.
Although the exact mechanism of mildew growth on a paint film has not yet been determined, considerable evidence suggests that mildew growth involves a sequence of bacterial and fungal attacks in which each attack renders the paint film susceptible to the metabolic processes of the next attacking organism. For effective mildew inhibition, a mildewcide must be active against a significant number of microbial species, bacterial and fungal, and especially effective against those species which cause initial damage to the paint film.
The addition of currently known mildewcidal agents such as 2-n-octyl-4-isothiazolin-3-one ("SKANE M-8") or N-pentachlorophenylethylenediamine to paint formulations provides excellent initial antimicrobial response in various paint films. However, these agents generally provide only temporary mildew inhibitions, since they are susceptible to chemical change and deactivation while still in the paint formulation, and to further deactivation in the paint film. Under outdoor environmental exposures these agents may also be subject to leaching from the paint films. A need clearly exists to develop a means of providing extended protection of paint films against mildew attack.
One method, proposed by Pittman, J. of Coatings Technology; 48(617), 31-7 (1976), of extending the effective life of a mildewcidal agent involves the chemical anchoring of the mildewcidal agent to a component in the paint film, e.g., the latex polymer, thus reducing the tendency of leaching of the agent from the paint film and effectively increasing the useful lifetime of the mildewcidal agent.
Lutz et al., Organic Coatings and Plastics Chemistry, Vol. 38, 195-201 (1976), describes the use of methyltrimethoxysilane to reinforce various organic formulations. Dried films of such reinforced latexes gave improved solvent resistance.
Other references forming part of the background of the present invention are: U.S. Pat. No. 3,253,009, which discloses silanes and siloxanes containing a moiety (RO)Si wherein R is a halogen-substituted aryl group; U.S. Pat. No. 3,542,786, which discloses compounds such as ##STR1## wherein X is chlorine or fluorine; U.S. Pat. No. 3,692,798 which discloses compounds of the formula ##STR2## wherein each of R.sub.1, R.sub.2, and R.sub.3 is lower alkyl or phenyl; U.S. Pat. No. 3,719,679, which discloses N-methyl- and N,N-dimethyl-3-[tris(trimethylsilyloxy)silyl]propanamine; U.S. Pat. No. 3,860,709, which discloses compounds such as that of the formula EQU (CH.sub.3 O).sub.3 Si(CH.sub.2).sub.3 NH(CH.sub.2).sub.2 NH.sub.2
and other simpler and more complex organosilicon amines and their salts; British Pat. No. 1,386,876, which discloses organosilicon quaternary ammonium compounds; Canadian Pat. No. 1,010,782, which discloses filled polymeric matrices containing solid fillers which fillers have coated on their surfaces organosilicon quaternary ammonium compounds; West German Offenlegungsschrift No. 1,806,758, which describes various phenolic and quarternary ammonium derivatives of phenyltrichlorosilane; and West German Offenlegungsschrift No. 2,632,417, which describes various organosilicon quaternary ammonium halides.
None of the above-noted references discloses or suggests the novel class of silane derivatives upon which the present invention is founded.